Special Weather Statement, NWS Des Moines, IA

Area Forecast Discussion
National Weather Service Des Moines IA
615 AM CDT Fri Jun 11 2021

...Updated Aviation Discussion...

.DISCUSSION.../Today through Thursday/
Issued at 330 AM CDT Fri Jun 11 2021

Main focus for the latest forecast package lies on the progression
of a thunderstorm complex currently marching across the Dakotas and
Nebraska. This activity will decay a bit as it tracks further east
from the parent upper wave and into more weakly forced/weakly
sheared environment, eventually turning south along the Mo River
Valley into western Iowa as the complex feeds into the instability
gradient and waning LLJ. Latest HRRR and ARW appear to have a decent
handle on the current radar trends, and both prefer a faster
progression with a decaying, outflow dominant complex tracking
through the western portion of the area this morning into early
afternoon. Confidence in precipitation chances wane into central
Iowa as the complex may break up or dissipate. Also quite skeptical
of model solutions suggesting a more widespread, organized
convective complex given the poor shear profiles and the
displacement of focused low level moisture convergence to our south
and west. Another shortwave crossing the northern Plains may support
additional isolated to scattered storm development later today
into tonight, but this scenario will be highly dependent on early
day convective evolution. Hi-res models are struggling to develop
much in the wake of the earlier convection, but trends will need
to be closely monitored through the day.

The rest of the forecast period continues to look very quiet as a
large ridge builds over the western two-thirds of the conus. Nearly
unanimous agreement between deterministic and ensemble outputs for
no precip this weekend through at least the middle of next week as
the as area remains devoid of any significant upper forcing or deep
moisture. NBM temps running on the warmer side of guidance with
daily highs around 90, but this is the preferred route at this time
given the recent warm/dry trends. Humidity levels will drop surface
below typical summer conditions as high pressure dropping south out
of Canada scours out a fair share of moisture. Models generate some
QPF over central Plains by mid-week as the ridge begins to break
down a bit, but any instability for convective development remains
shunted to our west.

&&

.AVIATION.../For the 12Z TAFS through 12Z Saturday morning/
Issued at 614 AM CDT Fri Jun 11 2021

VFR conditions forecast to prevail through the current TAF period.
TSRA moves through western Iowa this morning into the early
afternoon. Some scatterer activity on the eastern edge may impact
KFOD into KDSM, so have maintained a mention of VCTS for now.
These sites may need to be amended with a tempo group once tsra
spatial coverage and impacts becomes more clear.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

DISCUSSION...Martin
AVIATION...Martin

Hazardous Weather Outlook
National Weather Service Des Moines IA
350 AM CDT Fri Jun 11 2021

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-120900-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun-
Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-Greene-
Boone-Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-Jasper-
Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union-
Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne-
Appanoose-Davis-
350 AM CDT Fri Jun 11 2021

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

Scattered thunderstorms are expected today and into this evening.
A few strong storms may occur, especially over parts of southwest
Iowa. Damaging wind gusts are the primary threat.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

Special Weather Statement
National Weather Service Des Moines IA
841 AM CDT Fri Jun 11 2021

IAZ004-005-015-023-024-034-035-111445-
Palo Alto IA-Humboldt IA-Kossuth IA-Calhoun IA-Webster IA-
Pocahontas IA-Emmet IA-
841 AM CDT Fri Jun 11 2021

...A Line of Storms Across Northeastern Iowa Will Produce Gusty
Winds...

At 838 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Sherburn to 6 miles southwest of
Pocahontas. Movement was east at 40 mph.

Wind gusts up to 50 mph will be possible with these storms.

Locations impacted include...
Fort Dodge, Estherville, Algona, Emmetsburg, Pocahontas, Dakota City,
Humboldt, Laurens, Swan Lake, Five Island Lake, Ingham Lake, Iowa
Lake, Union Slogh, Fort Dodge Regional Airport, High Lake, Lost
Island Lake, Okamanpedan Lake, Silver Lake, Rush Lake and Armstrong.

LAT...LON 4350 9397 4253 9397 4256 9492 4350 9491
TIME...MOT...LOC 1338Z 270DEG 34KT 4365 9467 4267 9475

Hagenhoff